A trypsin-sensitive, cyclic nucleotide independent prokinase from rat brain supernatant contains a calmodulin-like subunit. It phosphorylates histone type II in a CA++-dependent manner, and histone type H-1 in a phospholipid dependent manner. It is inhibited by fluphenazine and fluphenazine-Sepharose affinity chromatography can dissociate its calmodulin subunit. HPLC and sedimentation equilibrium show that the enzyme contains several subunits without the presence of contaminating proteins.